You might think pollution in megalopolises like New York and Shanghai would be worse than, say, Denver. But don’t bet on that. The Agence France-Presse reports both the Big Apple and the Chinese city send less pollution into the air, per person, than Denver. That’s because people who live in cities with great public transportation systems tend to drive less. The Mile High City’s per capita emissions are nearly double those in New York—which has eight million inhabitants and a subway—and Shanghai. Denver emissions are sharply higher per capita than teeming Paris and Athens, too. Although the exact impact it would have on pollution levels is unclear, the Regional Transportation District has been working for years to modernize the transportation system throughout the metro area and beyond with a massive rail expansion.

But the FasTracks plan will need a lot more money to if it’s to be completed in full by 2027, as scheduled. As the Denver Post reports, RTD will come up about $2 billion short at current revenue levels, which are driven by a 0.4 percent tax (or four pennies on every $10). As such, RTD is likely to seek a 0.2 percent tax increase from Denver voters in order to complete rail lines to Lakewood/Golden, Boulder/Longmont, and Thornton/Northglenn by 2019 at an estimated cost of $7.2 billion. But officials don’t believe there is political support for doing more. The FasTracks project was approved in 2004 and has since been plagued by rising construction costs, the Denver Business Journal points out.